Method for suppressing the nitrification of ammonium nitrogen present in soil



The present invention relates to crop culture and is particularlyconcerned with a new agronomical practice and composition for conservingsoil nitrogen and for supplying the soil nitrogen requirements for plantnutrition.

Since the majority of plants obtain most or all of their nitrogenrequirements from the soil, the adequate provision of nutrient nitrogenin soil for plant growth is one of the foremost agronomic problems. Thenitrogen in the soil is found to occur primarily in three forms: organicnitrogen, ammonium nitrogen and nitrate nitrogen, of which ammoniumnitrogen and nitrate nitrogen are the primary forms utilized by plants.This nitrogen is absorbed by plants in solution from the soil in theform of ammonium ions and nitrate ions.

The organic nitrogen in the soil consists of a large number of compoundsand originates from manure, crop residues, organic fertilizers orbacterial syntheses. Since with the exception of the organic reducednitrogen fertilizers such as urea, the solubility of these compounds inwater is very low, they are not readily leached from the soil, butneither are they directly available to the plants for use. In order tobe available to the plants, the nitrogen in the organic compounds mustbe converted by soil bacteria to ammonia or inorganic ammonium salts.This conversion, when from organic reduced nitrogen fertilizers such asurea, takes place very rapidly, but very slowly when from other organicnitrogen compounds. Following the conversion, the ammonium nitrogen isvery rapidly oxidized by soil bacteria to inorganic nitrate nitrogen. Inthis process, the ammonium nitrogen is first oxidized to theintermediate nitrite nitrogen which is then rapidly oxidized to nitratenitrogen. This mineralization of organic nitrogen constantly replenishesthe soil with nitrogen available for plant absorption.

The ammonium nitrogen in the soil is derived from bacterial conversionof oragnic nitrogen or from the added reduced nitrogen fertilizers suchas anhydrous ammonia, aqueous ammonia, ammonium phosphate, ammoniumnitrate and ammonium sulfate. These ammonium compounds or inorganicreduced nitrogen compounds are readily soluble in Water or aqueous soilmedium. When in solution, the reduced nitrogen occurs largely as theammonium ion. Due to the cationic nature of this ion, the ion isstrongly adsorbed on the soil colloids or base exchange complex of thesoil. This colloidal-bound ammonium nitrogen exists in equilibrium witha small concentration of ammonium ions in the soil solution. Thus, thecolloidal-bound ammonium nitrogen provides a dynamic nitrogen reservoirto maintain a supply of ammonium ions in the soil solution for plantadsorption. Further, since the ammonium nitrogen in the soil occursprincipally as colloidal-bound nitrogen, only very small quantities ofthe ammonium form of soil nitrogen are lost from the feeding zone of theplants by leaching.

The nitrate nitrogen in the soil is derived from the oxidation ornitrification of ammonium nitrogen by soil bacteria, or by the additionof inorganic nitrate fertilizers such as ammonium nitrate, sodiumnitrate, potassium nitrate and calcium nitrate. The inorganic nitratecompounds are readily soluble in water and the aqueous atent C p3,%9,8@5 Patented Nov. 21, 1951 soil medium. When so dissolved, thenitrate nitrogen largely exists as the nitrate ion. Because of theanionic nature of this ion, nitrate nitrogen is not adsorbed by soilcolloids. Accordingly, the nitrate nitrogen is rapidly leached byrainfall and irrigation and readily lost from the feeding zone of theplants. Further, the nitrate nitrogen is reduced by many soil bacteriato nitrogen gas. The latter process is known as denitrification andaccounts for an additional loss of large quantities of nitrate nitrogenfrom the soil. The yearly loss from leaching and denitrification amountsto from 20 to percent of the nitrate nitrogen found in the soil,Whatever its source. Nitrification or the conversion of the ammoniumnitrogen in soil to nitrate nitrogen by bacterial action occurs at arate which is dependent primarily upon the soil temperature and the soilpH. The rate is also somewhat dependent upon the type of soil and themoisture content of the soil. The rate of nitrification is rapid whenthe soil temperature is at least 10 C. and the soil pH is at least 5.For example, the conversion of ammonium nitrogen to nitrate nitrogen insand, silt or clay loam soil having a pH of at least 6 may take place ata rate of from 20 pounds of nitrate nitrogen per acre per week at 10 C.,to 500 pounds of nitrate nitrogen per acre per week at 35 C. Even attemperatures as low as 2 C. nitrification Will oftentimes occur in suchsoils at a rate of 25 pounds of nitrate nitrogen per month. Thus,ammonium nitrogen is very rapidly changed to nitrate nitrogen in mostagricultural soils.

The tremendous losses of soil nitrogen resulting from the rapidnitrification of ammonium nitrogen, and the leaching and bacterialdecomposition of nitrate nitrogen have depleted many agricultural soilsof the nitrogen reserves and nitrogen requirements for plant nutrition.In order to replenish the soil nitrogen, the agriculturalist hasresorted to the use of large amounts of nitrate fertilizers and reducednitrogen fertilizers. In many instances, multiple fertilizer treatmentsduring the growing season have been required to maintain adequate nitrogen requirements for plant growth. In this practice, the greaterproportion of the employed fertilizers is in the form of reducednitrogen fertilizers. By the expression reduced nitrogen fertilizers ismeant fertilizers containing nitrogen in the reduced state and isinclusive of ammonium salts, ammonia, and Water-soluble organiccompounds readily convertible in soil to ammonia or ammonium ions.

Since the nitrogen must be present as nitrate nitrogen beforesubstantial quantities can be leached from the soil or lost bydenitrification, the application of nitrogen as reduced nitrogenfertilizers provides the agriculturalist with a short interval duringwhich available reduced nitrogen is at a maximum and conditions forleaching and denitrification are at a minimum. This interval isparticularly advantageous during the initial growth of seeds andemerging seedlings when high soil nitrogen concentrations are verydesirable. In addition, the ammonium nitrogen absorbed by plants isimmediately available for assimilation into organic materials beingsynthesized thereby. In contrast, the nitrate nitrogen must be reducedbefore it can be assimilated in the synthesis of plant materials. Thisreduction is carried out in the plant usually at the expense ofsynthesized carbohydrate. Although some plants seem to do well on eitherammonium nitrogen or nitrate nitrogen as a source of nitrogen nutrients,many plants such as potato, corn, rice, buckwheat, pineapple, cotton andorange prefer ammonium nitrogen and appear to grow best in the presenceof substantial amounts of this form of nitrogen. Thus, the need for amethod of suppressing the rapid loss of soil nitrogen is well recognizedby agriculturalists.

An object of the present invention is to provide a new and improvedagronomic practice for conserving soil nitrogen. A further object is theprovision of a new and improved method for suppressing the loss of soilnitrogen. An additional object is the provision of a new and improvedmethod for suppressing the loss of ammonium nitrogen from soil. Anotherobject is the provision of a new and improved method for supplying soilwith nitrogen avail-able for plant growth. Another object is theprovision of a new and improved method for suppressing the loss ofreduced nitrogen fertilizer supplements from soil. An additional objectis the provision of a new and improved method for suppressing thenitrification of ammonium nitrogen in soil. Another object is theprovision of a new and improved method for suppressing the conversionsoil of ammonium ions to nitrate ions. An additional object is theprovision of novel compositions to be employed in the new methods of thepresent invention. Other objects will become apparent from the followingspecification and claims.

The new agronomical practice for improving plant nutrition andconserving soil nitrogen comprises treating plant growth media with anitroanilide having the formula wherein X represents hydrogen, chlorineor methyl, R represents hydrogen or methyl and R represents formyl,acetyl or propionyl. The nitroanilides are solids adapted to be readilyand conveniently distributed in soil.

By the practice of this invention, the nitrification of ammoniumnitrogen in the soil to nitrate nitrogen is suppressed therebypreventing the rapid loss of ammonium nitrogen from the soil.Furthermore, by proper distribution, this action of inhibiting thetransformation of ammonium nitrogen to nitrate nitrogen is effectiveover a prolonged period of time. The ammonium nitrogen may arise fromadded ammonium nitrogen fertilizers or be formed in the soil byconversion of the organic nitrogen constituents found in soil or addedthereto as components of organic fertilizers.

The provision of an effective dosage of the nitroanilides in the soil orgrowth medium is essential for the practice of the present invention. Ingeneral, good results are obtained when the growth medium is suppliedwith the nitroanilide in the amount of from 2 to 150 parts or more byweight per million parts by weight of growth medium. In fieldapplications, the nitroanilide may be distributed in the soil in theamount of at least 0.5 pound per acre and through such a cross-sectionof the soil as to provide for the presence therein of .an effectiveconcentration of the agent. It is usually preferred that thenitroanilide be distributed to a depth of at least two inches below thesoil surface and at a dosage of at least 0.7 pound per acre inch ofsoil. By dispersing very large dosages in growth media, a prolongedinhibition of nitrification may be obtained over a period of manymonths. The concentration of the active nitroanilide compound iseventually reduced to a minimum by decomposition in the soil.

In one embodiment of the present invention, the nitroanilide isdistributed throughout the growth media prior to seeding ortransplanting the desired crop plant.

In another embodiment, the soil in the root zone. of growing plants istreated with the active compounds in an amount effective to inhibitnitrification but sublethal to plant growth. In such operations, thecompounds should be supplied in the soil in an amount no greater thanabout 50 parts by weight per million parts by weight of the soil. Byfollowing such practice, no adverse effect is exerted by thenitroanilide upon growth of seeds or plants. Oftentimes it is desirableto treat the soil adjacent to plants, and this procedure may be carriedout. conveniently in side-dressing operations.

In a further embodiment, soil may be treated with the nitroanilidefollowing harvest or after fallowing to prevent rapid loss of ammoniumnitrogen and to build up the ammonium nitrogen formed by conversion oforganic nitrogen compounds. Such practice conserves the soil nitrogenfor the following growing season.

In an additional embodiment, the soil is treated with the nitroanilidein conjunction with the application of reduced nitrogen fertilizers. Thetreatment with the nitroanilide may be carried out prior to, subsequentto or simultaneously with the application of fertilizers. Such practiceprevents the rapid loss of the ammonium nitrogen added as fertilizer andthe ammonium nitrogen formed from the organic reduced nitrogen infertilizers by the action of soil bacteria. The administration to thesoil of. the nitroanilide as a constituent of an ammonium nitrogenfertilizer composition contitutes a preferred embodiment of the presentinvention.

The present invention may be carried out by distributing thenitroanilide in an unmodified form through growth medium. The presentmethod also embraces distributing the compound as a constituent inliquid or finely divided solid compositions. In such practice, thenitroanilide may be modified with one or more additaments or soiltreating adjuvants including water, petroleum distillates or otherliquid carriers, surface-active dispersing agents, finely divided inertsolids and nitrogen fertilizers. Depending upon the concentration of thenitroanilide, such augmented compositions may be distributed in the soilwithout further modification or be considered concentrates andsubsequently diluted with additional inert carrier to produce theultimate treating compositions. The required amount of the nitroanilidemay be supplied to growth media in from 1 to 50 gallons of organicsolvent carrier, in from 5 to 27,000 or more gallons of aqueous carrier,or in from about 20 to 2,000 pounds of solid carrier per acre treated.When the compound is dispersed in an organic solvent carrier, it may befurther dispersed in the. above volume of aqueous liquid carrier.

The concentration of the compounds in compositions to be employed forthe treatment of growth media is not critical and may vary considerablyprovided the required dosage of effective agent is supplied to thegrowth media. The concentration of the nitroanilide may vary from 0.001percent by weight to percent by weight of the composition, depending onwhether the composition is a treating composition or a concentratecomposition and whether it is in the form of a solid or a liquid. Inaqueous liquid treating compositions, concentrations of from 0.001percent to 0.25 percent by weight of the anilide compound is consideredthe preferred composition. The concentration of the anilide compound inorganic solvents may be from 2.0 to 50 percent by weight. Concentrateliquid compositions generally contain from 2.5 to 50 percent by weightof the nitroanilide compound. Solid compositions may contain thenitroanilides in amounts as high as 95 percent by weight of the activecompound. Treating compositions generally contain 0.004 percent to 10percent by weight of the anilide compound. Concentrate compositionsoftentimes may contain from 2.5 to 95 percent of the nitroanilidecompound.

Liquid compositions containing the desired amount of the nitroanilidemay be prepared by dispersing the latter in one or more liquid carrierssuch as water or an organic solvent with or without the aid of asuitable surface-active dispersing agent or emulsifying agent. Suitableorganic solvents include acetone, diisobutylketone, methanol, ethanol,isopropyl alcohol, diethyl ether, toluene, methylene chloride,chlorobenzene and the petroleum distillates. The preferred organicsolvents are those which are of such volatility that they leave littlepermanent residue in the soil. When the solutions of nitroanilidecompound in organic solvents are to be further diluted to produceaqueous dispersions, the preferred solvents include acetone and thealcohols. When the liquid carrier is entirely organic in nature,particularly desirable carriers are the petroleum distillates boilingalmost entirely under 400 F. at atmospheric pressure and having a flashpoint above about 80 F. Dispersing and emulsifying agents which may beemployed in liquid compositions include condensation products ofalkylene oxides with phenols and organic acids, alkyl aryl sulfonates,polyoxyalkylene derivatives of sorbitan esters, complex ether alcohols,mahogany soaps and the like. The surface-active agents are generallyemployed in the amount of from 1 to 20 percent by weight of thenitroanilide compound.

Solid compositions containing the active nitroanilide compound may beprepared by dispersing the latter in finely divided inert solid carrierssuch as talc, chalk, gypsum, vermiculite, bentonite and the like,fullers earth, attapulgite and other clays, various solid detergentdispersing agents and solid fertilizer compositions. In preparing suchcompositions, the carrier is mechanically ground with the anilidecompound or wet with a solution thereof in a volatile organic solvent.Depending upon the proportions of ingredients, these compositions may beemployed without further modification or be considered concentrates andsubsequently further diluted with solid surface-active dispersing agent,talc, chalk, gypsum or the like to obtain the desired treatingcomposition. Furthermore, such concentrate compositions may be dispersedin water with or without added dispersing agent or agents to prepareaqueous soil treating compositions.

Soil treatment compositions may be prepared by dispersing thenitroanilides in fertilizers such as ammonium fertilizer or organicnitrogen fertilizer. The resulting fertilizer composition may beemployed as such or may be modified such as by dilution with additionalnitrogen fertilizer or with inert solid carrier to obtain a compositioncontaining the desired amount of nitroanilide for treatment of soil.Further, an aqueous dispersion of the nitroanilide compound fertilizercomposition may be prepared and administered to the growth medium.Fertilizer compositions comprising the anilide compound in intimateadmixture with ammonium fertilizers constitute preferred embodiments ofthe present invention.

In fertilizer compositions comprising a reduced nitrogen fertilizer, itis desirable that the nitroanilide be present in an amount of at least0.5 percent by weight based on the weight of the nitrogen present in thefertilizer as reduced nitrogen. Thus, when a fertilizer compositioncontains both reduced nitrogen and other forms of nitrogen such as inthe case of ammonium nitrate fertilizer compositions, the amount isbased on the weight of nitrogen present in the ammonium component.

In operations carried out in accordance with the pressent invention, thesoil may be impregnated in any convenient fashion with the nitroanilideor a composition containing the latter. For example, these modified orunmodified compositions may be mechanically mixed with the soil; appliedto the surface of soil and thereafter dragged or disced into the soil toa desired depth; or transported into the soil with a liquid carrier suchas by injection, spraying or irrigation. When the distribution iscarried out by introducing the nitroanilide in the water employed toirrigate the soil, the amount of water is varied in accordance with themoisture content of the soil in order to obtain a distribution of thenitroanilide to the desired depth. The nitroanilide may be readily andconveniently distributed to a depth of from two to four feet byirrigation methods. The preferred methods embrace procedures using anyof these steps or combination of steps wherein the compounds aredistributed in the soil substantially simultaneously with a reducednitrogen fertilizer.

The following examples illustrate the invention but are not to beconstrued as limiting.

' EXAMPLE 1 An aqueous ammonium fertilizer composition containing 1,000parts by weight of nitrogen and 50 parts by weight ofN-methyl-4-nitroformanilide per million parts of aqueous medium wasprepared by dispersing a 4 percent (weight by volume of solvent) acetonesolution of N-methyl-4-nitroformanilide in aqueous ammonium sulfatesolution. (The amount of nitrogen in all examples is based on thenitrogen present in the fertilizer in the reduced form.)

The composition so prepared was employed to treat seed beds preparedfrom sandy loam soil having a pH of about 8, containing essentially noorganic material and having been freed of nitrite and nitrate nitrogenby prior thorough leaching with water. In the treating operation, thecomposition was applied to the seed beds as a soil drench, and the soilin the beds thoroughly mixed to insure a substantially uniformdistribution of the composition throughout the soil. The amount ofcomposition employed was sufiicient to supply 200 parts by weight ofnitrogen and 10 parts by Weight of N-methyl-4-nitroformanilide permillion parts by weight of soil. In a check operation, other seed bedswere prepared of soil also freed of nitrite and nitrate nitrogen,containing the same amount of acetone and ammonium sulfate but noanilide compound. The composition was applied in an amount sufiicient tosupply the same concentration of nitrogen to the soil as the treatingcomposition containing N-methyl-4-nitroformanilide. The soil temperatureof all seed beds was maintained at about 70 F. for the period of thedetermination.

At various intervals following treatment, samples of soil Were takenfrom the different seed beds and the extent of nitrification of theadded ammonium sulfate fertilizer determined by analyses for combinednitrate plus nitrite nitrogen. The determinations were carried out byextracting the nitrate and nitrite from the soil with a saturatedcalcium sulfate solution, developing color in the clear supernatant ofthe extract with diphenylamine in sulfuric acid and comparing the colorwith a standard solution containing known concentrations of nitrate andnitrite ions. This procedure is similar to that described inColorimetric Methods of Analysis, by F. D. Snell and C. T. Snell, D. VanNorstrand Company, Inc., volume II, 3rd edition, page 801.

The percent nitrification in the seed beds of the added ammonium sulfateat various intervals is set forth in the following table:

Table I Percent nitrification Interval following Soil treated treatmentwith Soil treated in days ammonium with ammosulfate+N- nium sulfatemethy1-4- (check) nitroforrnanilide EXAMPLE 2 7. nitroformanilide inaqueous ammonium sulfate solution. The composition was applied to soilbeds in an amount sufiicient to give a concentration therein of 5 partsby weight of N-methyl-4-nitroformanilide and 100 parts by weight ofnitrogen per million parts by weight of soil. The degree ofnitrification was determined after an interval of 7 days and found to be5 percent. A check operation carried out with a similar compositioncontaining no N-methyl-4'-nitroformanilide showed 100 percentnitrification.

EXAMPLE 3 Ammonium sulfate and an acetone solution containing 5 percent(weight by volume of solvent) of 4-chloro-2'- nitropropionanilide weredispersed in water to prepare an aqueous composition containing 200parts by weight of nitrogen and 125 parts by weight of4-chloro-2-nitropropionanilide per million parts by weight of ultimatemixture. This composition was applied to seed beds of sandy loam soilsimilar to that described in Example 1, in an amount suflicient toprovide 40 parts by weight of nitrogen and 25 parts by weight of4-chloro-Z'-nitropropionanilide per million parts by weight of soil. Acheck operation was simultaneously carried out on other seed bedsemploying a similar aqueous fertilizer composition but containing no4'-chloro-2-nitropropionanilide. The degree of nitrification wasdetermined after an interval of 7 days and 17 days and found to bepercent and 7 percent, respectively. A check operation carried out witha similar composition containing no 4'-chloro-2'-nitropropionanilideshowed 100 percent nitrification at both intervals.

EXAMPLE 4 An aqueous ammonium sulfate composition containing 1,000 partsby weight of nitrogen and 25 parts by weight of 3'-nitropropionanilideper million parts by weight of ultimate mixture was prepared in a mannersimilar to that described in the preceding examples. This compositionwas applied to sandy loam soil in an amount sufficient to provide 100parts by weight of nitrogen and 5 parts by weight of3-nitropropionanilide per million parts by weight of soil. A checkoperation was carried out simultaneously on other seed beds employing asimilar aqueous fertilizer composition but containing no3-nitropropionanilide.

At intervals following the treatment, samples of soil from the differentseed beds were analyzed for their content of nitrite plus nitratenitrogen and the percent nitrification of ammonium sulfate determined.The results are given in Table II.

Table II Percent nitrification Interval following Soil treated treatmentwith Soil treated in days ammonium with ammosulfate+3- nium sulfatenitropro- (check) pionanilide EXAMPLE 5 These compositions may bedispersed in water to produce aqueous compositions having desirablewetting and penetrating properties. These aqueous compositions are thenemployed to treatsoil in an amount sufficient to distribute the anilidecompounds therein in efiective concentrations. The concentrates may alsobe dispersed in aqua ammonia to prepare fertilizer compositions.

EXAMPLE 6 Fertilizer compositions are prepared as follows:

(A) 2'-methyl 3' nitroformanilide is mechanically mixed with ammoniumphosphate to prepare a reduced nitrogen fertilizer compositioncontaining 5 percent by weight of the anilide.

(B) 2-methyl-5-nitropropionanilide is mechanically mixed with ammoniumnitrate to prepare a reduced nitrogen fertilizer composition containing3 percent by weight of the anilide.

1(C) N-methyl-Z'-nitropropionanilide is mechanically mixed with urea toprepare a reduced nitrogen fertilizer composition containing 2 percentby weight of the anilide.

These fertilizer compositions are distributed in soil to supply thenitrogen requirements for plant nutrition. The treated soil is resistantto nitrification and provides nitrogen available for plant growth over aprolonged period of time.

EXAMPLE 7 Aqueous ammonium fertilizer compositions containing 1,000parts by weight of nitrogen and 50 parts by weight of 3-nitroacetanilidein a million parts of aqueous media were prepared by dispersing anacetone solution containing 4 percent (weight by volume of solvent) of3-nitroacetanilide in aqueous solutions of various ammonium compounds.

In operations similar to that described in Example 1, the soil invarious seed beds was treated with the above described compositions todistribute a particular composition throughout the soil in an amountsufficient to supply a concentration of nitrogen in the soil of 200parts by weight and of 3-nitroacetanilide of 10 parts by weight permillion parts by weight of soil. The treated soil was maintained at 70F. for the period of the operation. At various intervals, samples of thesoil were taken an analyses made to determine the extent ofnitrification.

Soils treated with the ammonium phosphates were analyzed for nitrateplus nitrite nitrogen as previously described. The soils treated withammonium nitrate were analyzed for residual ammonia by extracting thesoil with 2 molar potassium chloride and the ammonia in the extractdetermined by comparisons with a standard on a spot plate using Nesslersreagent as indicator.

Check operations were simultaneously carried out on other seed bedsemploying similar aqueous fertilizer compositions -but containing no3'-nitroacetanilide.

The results of the treating and check operations are given in Table III.

EXAMPLE 8 A solid fertilizer composition is prepared as follows: (1) aninhibitor component is prepared by (a) mixing and grinding together 0.2gram of 3'-methyl-2-nitroacetanilide and 0.3 gram of attaplugite, (b)adding 1.5 grams of pyrophyllite thereto and grinding the resultingmixture until a finely powdered uniform composition is obtained; (2) afertilizer component is prepared by ham mermilling together a 50:50mixture by weight of ammonium sulfate and pyrophyllite to obtain a fineuniform composition; (3) the inhibitor component and fertilizercomponent are mixed together in various ratios on a roller mill toobtain a soil treating composition containing 3'-methyl-2-nitroacetanilide in varying concentrations expressed in percentbased on the nitrogen in the composition. These compositions areemployed to fertilize various beds of sandy loam soil containingessentially no organic material and having a pH of about 8. The soilemployed is leached prior to use to remove all nitrate and nitritenitrogen constituents. A sufiicient amount of water is added to thevarious beds to give the soil in the beds varying moisture content. Thebeds are fertilized in areas to be planted by providing depressions andadding thereto the fertilizer treating composition and then covering thecomposition with soil. The amount of composition employed is suficientto supply 160 parts by weight of nitrogen per million parts by weight ofsoil. The soil is maintained in the temperature range of from 70 to 85F. for three weeks. At the end of this period, samples of soil areanalyzed for content of nitrate plus nitrite nitrogen to determine theextent of nitrification of the added ammonium sulfate. The results arecompared with determinations made on a check operation wherein afertilizer composition containing no 3-methyl- 2-nitroacetanilide isemployed. Samples of the soil treated with the fertilizer compositioncontaining inhibitor show no substantial amount of nitrate plus nitritenitrogen while samples of soil treated with fertilizer compositioncontaining no inhibitor show complete conversion of ammonium nitrogen tonitrate plus nitrite nitrogen.

EXAMPLE 9 Irrigation water is modified by adding an acetone solutioncontaining 5 percent (weight by volume of solvent) ofN-methyl-4-chloro-2'-nitroformanilide to give a concentration of theanilide compound therein of 50 par-ts by weight in a million parts ofwater.

The water modified as described above is employed to irrigate dry sandyloam soil having a pH of 8 and previously leached to remove any nitriteand nitrate present. The depth of the sandy loam bed is 14 inches. Anamount ofmodified water equal to 6 acre inches per acre is added andallowed to equilibrate in the soil by standing for several days. At theend of this period, samples of soil from various depths up to inches aretaken. To each sample a suificient volume of an aqueous ammonium sulfatesolution containing 2,500 parts of nitrogen by weight per million partsof Water is added to give a composition containing 100 parts "by Weightof nitrogen per million parts of soil. The fertilized soil samples arethereafter maintained in the temperature range of from 70 to 85 F. Atperiodic intervals, samples of the soil are taken and analyses made onthe nitrate plus nitrite nitrogen to determine the extent ofnitrification.

Analyses on samples of soil at various levels on the 7th and 20th dayafter the start of incubation show commercial control of nitrificationat levels to 10 inches depth.

In a check operation, determinations are carried out on the variouslayers of soil irrigated with unmodified water. It is found in the checkoperations that after 7 and 20 days there is 100 percent nitrificationat all depths up to 10 inches in the soil.

EXAMPLE 10 An aqueous soil treating composition containing 100 parts byWeight of 3'-nitroacetanilide, 1,000 parts by weight of nitrogen asammonium sulfate and 500 parts by weight of phosphorus as phosphoricacid was prepared 10 by dispersing a 4 percent (weight per volume ofsolvent) acetone solution of 3-nitroacetanilide into an aqueous solutionof ammonium sulfate and phosphoric acid.

Pots were prepared for planting with 500 grams of sandy loam soil havinga pH of 8 and a 4 percent moisture content. 200 milliliters of thetreating composition prepared as described above was poured over thesoil in the pots (an amount equal to about 1 inch of liquid) to supplyto the soil 3'-nitroacetanilide in an amount sufficient to give aconcentration of 40 parts by weight per million parts by weight of soiland a concentration of nitrogen of 400 parts per million. The treatedsoil was then covered with paper to reduce evaporation and maintained inthe temperature range of from 70 to F.

After a period of six weeks the soil in the pots was leached with 6inches of water and thereafter planted with three species. Each pot wasplanted with four tomato plants, five milo plants and a thick stand ofrye. After an appropriate growth interval, the tops of the plants wereharvested just above ground level and weighed. The average fresh weightin grams per pot was determined at the time of harvest which was 35 daysfor tomato plants, 46 days for milo plants and 47 days for rye plants.

A check operation was carried out simultaneously wherein soil in potswas similarly fertilized with a composition containing the same amountof ammonium sulfate, phosphoric acid and acetone but no3-nitroacetanilide.

The weights of the plant tops at harvest in both the treating and checkoperations are set forth in Table IV.

1. A method for suppressing the nitrification of ammonium nitrogenpresent in soil and preventing rapid loss of ammonium nitrogen therefromwhich comprises impregnating soil below the soil surface in the growingarea thereof in concentration sufficient to suppress nitrification, witha nitroanilide having the formula wherein X represents a member of thegroup consisting of hydrogen, methyl and chlorine, R represents a memberof the group consisting of hydrogen and methyl, and R represents amember of the group consisting of formyl, acetyl and propionyl, saidconcentration being from about 2 parts by Weight per million parts byweight of 2. A method according to claim 1 wherein the nitroanilide is-N-methyl-4'-nitroformanilide.

3. A method according to claim 1 wherein the nitroanilide is3-nitropropionanilide.

4. A method according to claim 1 wherein the nitroanilide is3-nitroacetanilide.

5 A method according to claim 1 wherein the nitroanilide isN-methyl-4-chloro-2'-nitroformanilide.

6. A method according to claim 1 wherein the nitroanilide is4-chloro-2'-nitropropionanilide.

7. A method according to claim 1 wherein the nitroanilide is added in anamount sufiicient to give a con- 11 centration in the soil of from 2 to50 parts by weight per million parts by weight of soil.

8. A method according to claim 1 wherein the nitroanilide is introducedin the soil at a point near the roots of the growing plants.

9. A method for treating soil to inhibit the conversion thereinofammonium nitrogen to nitrate and nitrite nitrogen and to prevent rapidloss of ammonium nitrogen therefrom which comprises impregnating thesoil below the soil surface in the growing area thereof in an amountsuflicient to inhibit nitrification with a composition comprising anitroanilide in intimate admixture with a soil treating adjuvant, saidnitroanilide having the formula in said reduced nitrogen fertilizer is afertilizer selected from the group consisting of ammonia, ammoniumsalts, 30

and urea.

11. A fertilizer composition comprising a major amount of a reducednitrogen fertilizer as source of ammonium ions and a nitroanilide havingthe formula wherein X represents a member of the group consisting ofhydrogen, methyl and chlorine, R represents a member of the groupconsisting of hydrogen and methyl, and R represents a member of thegroup consisting of formyl, acetyl and propionyl, and wherein thenitroanilide is present in a concentration of at least 0.5 percent byweight based on the weight of the reduced nitrogen present in thefertilizer, and wherein said reduced nitrogen fertilizer is a fertilizerselected from the group consisting of ammonia, ammonium salts, and urea.

12. A fertilizer composition comprising a major amount of a reducednitrogen fertilizer as a source of ammonium ions and 3-nitroacetanilideas the nitroanilide, and wherein said nitroanilide is present in aconcentration of at least 0.5 percent by weight based on the weight ofreduced nitrogen present in the fertilizer, and wherein said reducednitrogen fertilizer is a fertilizer selected from the group consistingof ammonia, ammonium salts and urea.

References Cited in the file of this patent UNITED STATES PATENTS2,226,672 Smith Dec. 31, 1940 2,314,091 Jones Mar. 16, 1943 2,627,490Bartlett et al. Feb. 3, 1953

1. A METHOD FOR SUPPRESSING THE NITRIFICATION OF AMMONIUM NITROGENPRESENT IN SOIL AND PREVENTING RAPID LOSS OF AMMONIUM NITROGEN THEREFROMWHICH COMPRISES IMPREGNATING SOIL BELOW THE SOIL SURFFACE IN THE GROWINGAREA THEREOF IN CONCENTRATION SUFFICIENT TO SUPPRESS NITRIFICATION, WITHA NITROANILIDE HAVING THE FORMULA